Spark plug



Feb. 23, 1937. A. E. ANDERSON SPARK PLUG Filed Aug. 3, 1935 v 3nnenkor; a. 5. fimdensoiz Bu w (Ittorneg Patented Feb. 23 1937 UNITED STATES PATENTIOFFICE SPARK PLUG August E. Anderson, Montclair, N. J. Application August a, 1935, Serial No. c4524 50mm. (or. 123-169) My invention relates to spark plugs for internal in an old metal housing a new porcelain unit, in-

stead of putting in a completely new spark plug. In this anner a considerable saving in costs to the user is made, because the metal housing may be used over and over again and only new porcelains need be obtained.

Another and very considerable advantage is also gained by the permanently set spark gap which is adjusted before the porcelain unit leaves the factory. The ground electrode, which consists of a ring or gasket with a projecting finger, is namely permanently secured near the inner end of the porcelain and the finger bent over towards the end .of the slightly protruding central or main electrode to obtain the ,desired spark gap with sliding spark. The ground electrode gasket may be secured on the porcelain either by cement or other adhesive or by screws, rivets or prongs.

Still another advantage of my spark plug is' obtained by the feature that the spark-gap is arranged deep in the metal housing and above the threaded portion thereof, that is, above the water jacket. This prevents cracking ofthe porcelain, These and other advantages are obtained by my invention which willbe further explained in the following description and illustrated in the apcompanying drawing, in which:

Figure 1 shows an axial section of my spark pl Fig.2 a bottom plan view of Fig. 1;

Fig. 3 a perspective view of the combined gasket and ground electrode used; i

Fig. 4 a modified form 01' the ground electrode; Fig. 5 a fragmentary elevation of the inner end of the porcelain unitfwith the ground electrode as electric l2.

A characteristic feature of the invention is that the inner end of the porcelain terminates with a tapering shank I3 quite a distance in from the end of the housing Ill when assembled therein and above the threaded portion itself. Themain electrode l5 which consists of a'straight pin extending all the way through the porcelain protrudes slightly with its spark point l6 beyond the end of the tapering shank l3 of the porcelain. The main electrode is threaded as at I! in the outer end of the porcelain in the usual manner and is provided with a screw cap l8 for securing the lead-in wire.

The porcelain [2 has an enlarged body portion 19 with upper and lower shoulders for gaskets 20 and 2| for which seats are provided in the securing nut H and the housing l0 respectively, whereby the porcelain is firmly secured in the housing It) when the nut II is drawn up tightly.

The upper gasket 201s of conical shape as is also the lower gasket 2|, which latter forms the It of the main electrode 15 which end IE only slightly projects beyond the shank [3 of the porcelain so as to form a" spark gap 23, well inside the open end of the metal housing. The spacing of the electrodes is hired by the end of shank ll of the porcelain. In order to assure the accurate position of the finger 22 to produce the desired sliding spark and a permanent width of the spark gap, an annular ledge 24 spaced therefrom and of less height than the tapered shank l3 and having its base diameter equal to the corresponding inner diameter of I the gasket or ground elecparts when assembled. The finger 22 is bent so as to follow the conical surface of the ledge 24' and project beyond its end terminating level with the end of the shank I 3. Furthermore, the two gaskets 20 and 2| are permanently secured on the shouldersof the body portion l9 of the porcelain. This-may be accomplished by means of an adhesive 25, Fig. 3, or by anumber of prongs 28 shown on the ground electrode 21 in Figs. 4 and 5. These prongs 26 are intended to be sprung over the end of the body portion 19 of the porcelain whether the same is smooth-faced or furnished with corresponding grooves for accommodating the prongs.

In Fig. 6 is indicated still another way of firmlyand premanently securing and positioning the trode 2! is provided so as to accurately locate the ground electrode 28 on the body portion ll of the porcelain, namely, by rivets, pegs, screws 29 or the like.

In Fig. 'l is shown the porcelain electrode unit assembled as sold on the market and which consists of the following parts: porcelain l2, main electrode it, screw cap I8, gasket and ground electrode II with finger 22. All that is needed;

in replacing a broken or injured porcelain is then to unscrew the securing nut I i, take out the old porcelain-and put in a new porcelain-unit and secure it in place by tightening up the nut H. No adjustment whatsoever will be necessary since the correct spark gap has already been set before the unit leaves the factory.

The renewal or spark plugs in this manner is considerably less costly-to the user and assures accurate width of the spark gap without special adjustment. 1

Moreover, the exchange of the porcelain units can be performed in a very short time. a

It should be noted that the seat for the ground electrode is located high up in the metal gasket and about level with the octagonal tightening collar 30.. As a consequence, the spark gap is also located well away from the open, threaded end ll of the metal housing It.

It should be understood that the invention is not limited to the details of construction here shown and disclosed, but that those may be varied widely without departing from the spirit of the invention as defined by "the claims.

I claim: a l

1. In a spark plug having a metal housing and a dielectric, and a slightly protruding'maincentral electrode in said dielectric; a ground electrode in the shape of an annular gasket with an inwardly bent finger adapted to form a sliding spark with said main electrode, and means for permanently securing said ground electrode on so finger adapted to form a sliding spark with said point, a ledge on the porcelain adapted to accurately locate the gasket with preadiusted gap betweensaid electrodes and means for permae nentlysecuring said gasket electrode on said porcelain.

3.-In combination with a metal spark plug housing, a unit comprising a porcelain adapted to be assembled in said housing, a central shank on said porcelain, a main electrode secured in the porcelain so as to slightly project with its point beyond the end thereof, a gasket electrode having an inwardly bent. finger adapted to form a sliding spark with said point, a ledge on the porcelain having a base of the same diameter as said gasket in order to accurately locate the finger with preadiusted gap between the electrodes and means for permanently securing said gasket elsetrode on said porcelain, said ledge forming a support for said gasket andflnger.

4. In combination with 'a metal spark plug ,housing, a unit comprising; a porcelain adapted to be assembled in said housing, a central shank on said porcelain, a main electrode secured in the porcelain and having a slightly projecting point beyond the end to! said shank, a gasket' between said electrodes and means for permanently securing said gasket electrode on said porcelain. I

5. In'combination with a metal spark plug housing, a unit comprisinga porcelain adapted to be assembled in said housing, a central electrode secured in the porcelain havingits point slightly protruding beyond the end of the porcelain, an annular ground electrode having an inwardly bent finger adapted to produce a sliding spark with said point, a ledge on, the porcelain adapted to accurately locate the ground electrode with pr'eadiusted gap between said electrodes and to provide an annular cooling space therefor, and means for permanently securing said ground electrode on said porcelain, said housing being provided with a seat for the unit in such a pod- 

